Improvement in projectiles



.J. M. PIOLLARD.

PROJECTILE. No."179.054. Patented June 20,1876.

WITNESSES: INVENTQR ATTORNEYS.

TNE NORRIS Firms co. PNOTO-LITHQ. WASHINGTON, m c.

formed by its converging JAMES M. POLLARD, OF NEW ORLEANS, LOUISIANA.

IMPROVEMENT IN PROJECTILES.

Specification forming part of Letters Patent No. 79,054,

December To all whom it may concern:

Be it known that I, JAMES M. POLLARD, of, New Orleans, in the parish of Orleans and State of Louisiana, have invented a new and Improved Projectile; and I do hereby declare that the following is afull, clear, and exact description of the same, reference being bad to the accompanying drawing, forming a part ofthis specification, in which Figure 1 is a side view of my improved projectile. ig. 2 is a similar view of a modification of the same.

The object of this invention is to provide a projectile of improved construction, designed to obviate to a great extent the objections arisin g from the resistance of the air, and adapted, by reason of its particular construction, to a much greater velocity and accuracy of movement during its flight. It consists in a projectile having a central cylindrical portion, with endssymmetrically tapered to a conical or paraboloidal form, the rear end of the projectile being upset or molded with a raised bar, which is of less diameter than the cylindrical portion, and has a convex end. The double paraboloidal form adapts the projectile to the least resistance from the air. The raised burr acts in the nature of a guide as a feather to an arrow. lts rear convex face receives the impact from the powder, and its central cylindrical portion centers the projectile in the gun and preserves its proper longitudinal axis.

In the drawing, Arepresents a projectile of my improved construction, having its ends symmetrically tapered into the double conical or paraboloidal form, in which the angle sides is about twenty degrees.

It is a well-known fact that projectiles passing through the air with a high velocity meet with a great retardation, which is proportionate to the velocity. This is due to the fact that the air in front of the moving body is compressed by reason of its inertia,-which renders its displacement a resistance, and also due to the retardation caused by a vacuum in its rear, for, as air rushes into a vacuum only at the rate of 1,366 feet per second, it is obvious that if the velocity of the projectile be greater the air cannot follow sufiiciently rapid to fill dated June 20, 1876; application filed 10, 1875.

in the vacuum, and even if the velocity be less than 1,366 feet per second-a partial vacuum or rarclaction of the atmosphere operates with the same efl'cct, but of less degree.

To obviate these objections I make the projectile with a conical or paraboloidal front end, to displace the air with the least resistance, and with a similarly shaped rear end, to accommodate the replacement, with theleast' ob:

jectionable effects of a vacuum in the rear. The rear end of the projectile is, however, upset or molded so as to form a raised burr, a,.of less diameter than the central part of the projectile. This burr acts in the nature of a feather to an arrow' to keep its longitudinal axis coincident with the line of its flight.

I am aware of thefa-ct thataseries ofgrooves have been constructed around the rear portion of a cylindrical projectile to efi'ect this result, but this is inefi'ective for the following reasons: First, the grooves being upon the periphery of the projectile, they are, when closely fitted to the bore of the gun, more or less eft'aced by abrasion with the interior of the bore in its passage out. In the second place, also, the grooves being a long distance from the longitudinal axis, the angular resistance which they form to the center of gravity is such as to cause the projectile to wabble.

By making a burr upon the rear portion of a tapering projectile, it will be seen that its integrity can never be efl'ectcd by abrasion with the gun, for, being of less diameter, it can never come in contact with the same, and, moreover, being of less diameter than the central part of the shot, its resistance is more nearly in alignment with the center of gravity of the shot, and, as a natural result, it better preserves the longitudinal axis of the same during its flight. As shown, the rear end of the bullet is convex, against which a large per cent. of the trajectorytension of the powder is exerted to discharge the projectile.

For large-sized projectiles for ordnance, the burr upon the rear will preferably be made in the form of a detachable cap, and fastened to the shot by suitable means, while, with bullets, it is preferably molde in one piece. With soft metal bullets, however, it may not even be necessary, under some circumstances, to have a complete burr before firing the bullet,

. as the latter may be arranged with a hard bore, and in so doing prevents the projectilefroni wabbling upon its transverse diameterin its passage out. This is an important advantage in connection'with a projectile having the improved burr, for, although the burr is of aless diameter than the center of the projectile, if

. the latter were to vibrate upon its transverse diameter, it would bring, probably, one side or the other of the burr against the inside of the gun, and rub off the burr on that side, which would cause the bullet to constantly diverge from its path, after it left the gun, upon the side opposite that abraded. This would occur in almost every instance, and would be disastrous, so far as accuracy is concerned.

Upon the rear portion of the cylindrical part of the projectile is formed a raised flange or ring, 0, which is designed to form a gascheck. This flan ge is placed between the center of gravity and the rear end of the projectile, so that its frictional resistance with the side of the gun will be a pulling strain, which tends to preserve the proper position of the projectile in its passage out oi the gun.

Having thus described my invention, what I claim as new is- 1'. A double-conical or double-paraboloidal projectile, having a raised burr on its rear end of less diameter than the center of the projectile, as and for the purpose described.

2. A double-conical or double-paraboloidal projectile, havinga central cylindrical portion and a raised burr on the rear end, of less diameter than said cylindrical portion, as and for the purpose described.

J. M. POLLARD.

Witnesses:

SOLON C. KEMON, Guns. A. PETTIT. 

